The present invention relates to the art of remote light admittance control for television cameras and more particularly to an automatic ranging iris control. A televised scene may vary widely in the average level of illumination. The imaging tubes used for television cameras cannot respond to such wide variations of light levels and some means must be provided to regulate the amount of light reaching the tube from the scenes.
A motor driven iris is commonly provided in the cameras with some control means for controlling the iris. It is desirable that this iris control be manually controlled from a remote location. It is desirable from the standpoint of the operator that this remote control be a single lever type control.
Because of the required wide range of the iris, a separate ranging switch is normally used to select the range in which the iris control will operate. This is to provide the operator with a control with adequate resolution to control the iris with accuracy.
In the newer cameras it is desirable to use a digital remote control system for all controls. In an effort to reduce the amount of structure it is desirable to limit the code to, for example, a single eight-bit code. This presents a problem when more than a eight-bit code is necessary to provide the desired resolution.